托福阅读材料:What’s a Fly Doing in Antarctica?

　　南极对于许多生物来说是荒芜严寒恐怖的死亡大陆，尤其是像苍蝇这样喜欢生活在炎热区域的昆虫。而近来科学家却在南极发现了苍蝇，这是怎么回事呢?下面的新托福考试阅读练习资料里我们会为大家详细介绍。

　　Sometimes the biggest finds are the smallest finds. Researchers examining a segment of siltstone taken from ground along the Beardmore glacier in Antarctica found something unexpected. They found a fly.

　　Well, not exactly a fly. They found a fly fossil–it’s a segment of the exoskeleton, the protective shell, of a fly larva. While the larvae are still growing, they are protected by a thin shell. And where there’s larval shell, there are flies. So what are flies doing in Antarctica? It’s much too cold there for flies. And the closest fly-friendly location, South America, is thousands of miles away.

　　Part of the answer is that the fly fossil is ancient–it was found with a number of other fossilized things that have been dated between three million and seventeen million years old. It’s possible that the fly lived during a period when sea levels were much lower there than they now are. Lower sea levels means wider continents –think of standing on the edge of a beach and having the water pull back. And wider continents means it’s more likely that living things might travel across the gap.

　　Or maybe not. Maybe flies are much older than anyone thought. We know that what we now call Antarctica was once connected to both South America and Australia. But that was around eighty million years ago, and flies aren’t thought to be that old.

　　Whatever the answer is, something in our understanding of the continents, the seas, or fly evolution has to be fixed. That’s one of the best things about science–a really big change can come from the discovery of something really small.